1. Field of the Invention
The present invention relates to an imaging device that electronically captures an image through a lens system.
2. Description of the Related Art
In photography, a bokeh or blurring technique using an effect of the depth of field is often used to blur a background and/or foreground view that does not include the main subject, which is in focus. However, the depth of field deepens as the focal length is reduced; therefore the bokeh effect in a compact digital camera with a relatively small image sensor is ineffective because such a camera requires a short focal length.
For the above-mentioned problem, there is provided a method that determines in-focus areas and out-of-focus areas of a captured image to produce an artificial bokeh effect by applying a blurring process to the images within the out-of-focus areas. In this method, a captured image is divided into a plurality of areas and the in-focus areas and the out-of-focus areas are determined by evaluating the spatial frequencies of each area. Namely, an area with high spatial frequencies is determined to be an in-focus area and an area with low spatial frequencies is determined to be an out-of-focus area. This determination is based on the fact that the in-focus areas generally have high contrast (refer to U.S. Pat. No. 7,454,134).